1. Field of the Invention
The present invention concerns a high- and medium-voltage gas blast circuit breaker comprising a cylindrical metal or insulative enclosure filled with pressurized insulative gas, a fixed arc contact and a mobile assembly coupled to an operating member comprising a gas blast cylinder associated with a gas blast nozzle and cooperating with a piston, and a mobile arc contact carried by a tubular member inside the gas blast cylinder.
2. Description of the Prior Art
Circuit breakers of the above type are known.
The tubular member carrying the mobile arc contact often has lateral openings to obtain a double gas blast effect in the sense that the pressurized gas in the annular space between the gas blast cylinder and the tubular member supporting the mobile arc contact is blown inside the gas blast nozzle and also towards the interior of the mobile arc contact and therefore towards the interior of the tubular member supporting it.
An object of the present invention is to improve the operation of a circuit breaker of this kind and in particular of thermal expansion circuit breakers using the energy of the arc by increasing the gas pressure near the mobile arc contact by means of a particularly simple and low-cost arrangement.